Stored energy type closing device for an electric circuit breaker



Nov. 18,1958 RE 2,861,144

J. A. FA STORED ENERGY TYPE CLOSING DEVICE FOR AN ELECTRIC CIRCUITBREAKER Filed July 8, 1957 2 Sheets-Sheet 1 Inventor: John A. F vre,

His torneg.

1958 J. A. FAVRE 2,861,144

STORED ENERGY TYPE CLOSING DEVICE FOR AN ELECTRIC CIRCUIT BREAKER FiledJuly 8, 1957 2 SheeLs-Sheet 2 Inventor:

y aa gs i iz w torneg.

United States Patent STORED ENERGY TYPE CLOSING DEVICE FOR AN ELECTRICCIRCUIT BREAKER John A. Favre, Bromall, Pa., assignor to GeneralElectric Company, a corporation of New York Application July 8, 1957,Serial No. 670,404

11 Claims. (Cl. 20082) This invention relates to a stored-energy type ofclosing device for an electric circuit breaker and, more particularly,to a closing device of this general type in which pressurized fluid,preferably liquid, is utilized for charg ing a spring, which issubsequently released to produce circuit breaker closing.

The use of pressurized liquid for the operation of a circuit breaker hasusually required a number of relatively complex control valves and alsoa relatively expensive accumulator for storing a charge of compressedgas, which provides the energy for closing the breaker.

It is an object of the present invention to provide a simple andinexpensive circuit-breaker closing device which is controlled bypressurized liquid but which requires no accumulator or complex controlvalves for its proper operation.

Another object of my invention is to provide a simple and reliableclosing device in which pressurized fluid is utilized for charging aspring which can be subsequently released to produce circuit breakerclosing.

Another object of my invention is to insure that premature operation ofthe hydraulically-controlled springcharging means does not interferewith or defeat discharging of the spring during a normal closingoperation.

In carrying out my invention in one form, I provide a chargeable springwhich is dischargeable at one of its ends to produce closing of thecircuit breaker. A movable piston mounted within a cylinder isoperatively coupled to said one end of the spring. Pressurized fluidsupplied to the cylinder space at one side of the piston acts to drivethe piston in a direction to charge the spring. When the spring ischarged, a suitable latch holds the piston in a position which maintainsthe spring charged. Subsequent release of the latch allows the spring todischarge and drive the piston in a direction opposite to the chargingdirection, and this action is used to produce circuit breaker closing. Adump passage leading from the cylinder space is sealed off during thespring-charging operation, but this dump passage is opened duringspring-discharging to allow closing action to take place withoutappreciable restraint from fluid in the cylinder space.

Control of fluid flow through the dump passage and also through theinlet to the cylinder space is provided by means of a pressure-sensitivemovable valve element. During a spring-charging operation, this valveelement seals off the dumping passage, but upon spring-discharge thisvalve element is driven out of sealing relationship with the dumpingpassage and into a position where it acts to block flow through theinlet. This insures that no fluid will be inadvertently supplied throughthe inlet to the cylinder during a spring-discharging operation, thuspreventing spring discharging from being defeated by any such fluid.

For a better understanding of my invention, reference may be had to thefollowing specification taken in connection with the accompanyingdrawings, wherein:

Fig. 1 is a schematic view partially in cross-section showing a circuitbreaker closing arrangement embody- "Ice ing my invention. The circuitbreaker is in open position with the closing device fully charged.

Fig. 2 is a view similar to that of Fig. 1 but with the parts of theclosing device in a position through which they would pass near the endof a closing operation.

Fig. 3 is a view illustrating a portion of the circuit breaker mechanismshortly after being tripped to open position.

Fig. 4 is a cross-sectional view illustrating a modification of oneportion of the closing arrangement shown in Figs. 1-3.

Referring now to Fig. 1, the stored energy closing device is shown at10, and the circuit breaker which it is designed to close is shown at12. This circuitbreaker 12 can be of any suitable conventional type andis accordingly shown in schematic form only. 7

As shown in Fig. 1, circuit breaker 12 comprises a pair of relativelymovable interrupting contacts 18 and 19. One of these contacts 18 ispivotally mounted at 18a and is biased to the open circuit positionshown by a suitable spring 20. Closing forces are transmitted to themovable contact 18 by a conventional trip-free operating mechanism Mwhich comprises a pair of toggle links 21 and 22 pivotally joinedtogether by a knee 23. One of the toggle links 21 is pivotally connectedat its opposite end to movable contact 18, whereas the other of thetoggle links 22 is connected by a pivot pin 22:; to the upper end of aguide link 24. This guide link 24 is pivotally supported at its lowerend on a fixed ful-' crum 26. The pivot pin 22a carries a latch roller28 which cooperates with a suitable trip latch 30 pivotally mounted at31. So long as the trip latch 30 remains in the latched position shown,the toggle 21, 22 is capable of transmitting thrust to the movablecontact 18. Thus, when the knee 23 is lifted from the position shown inFig; 1, the toggle 21, 22 is extended and drives the movable contact 18toward the closed circuit position.

This lifting of the knee 23 is accomplished by the action of a suitableplunger 35 cooperating with the usual roller 36 which is mounted at theknee 23. When this plunger 35 is driven upwardly from its position ofFig. 1, it lifts the knee and produces closing of the circuit breaker inthe manner described hereinabove. Preferably, the plunger 35 is arrangedto drive the toggle 21, 22 slightly overcenter and against a stop 37 sothat the movable contact will be held in closed circuit position evenwhen the plunger 35 is returned to its original position of Fig. 1.

A suitable solenoid is provided for controlling the trip latch 30.Energization of this solenoid 32 in response to predetermined electricalconditions causes the solenoidto drive the latch 30 counterclockwiseabout its pivot 31 to effect tripping open of circuit breaker. Shouldthe latch 30 be tripped when the circuit breaker is closed, or evenduring the closing stroke, the pivot 22a will be freed by such trippingaction, and as a result, the toggle 21, 22 will be rendered inoperativeto transmit thrust to the movable contact 18. As a result, the openingspring 20 will be free to drive the movable contact to its openposition.

The position of the parts of the mechanism after such tripping hasoccurred is shown in Fig. 3, where the plunger 35 is shown still in itselevated position. A suitable resetting spring 38 connected to the guidelink 24 and tending to rotate the guide link clockwise about its fulcrum26 tends to reset the mechanism M to a latched, thrusttran'smittingcondition but is incapable of achieving this resetting action so long asthe plunger 35 remains out of its normal position of Fig. 1. As shown inFig. 3, the plunger 35 acts to block such resetting action while in itsraised position, and only when it is returned to its position of Fig.lis it moved out of interfering relation.-

ship with the roller 36 to permit the resetting spring 38 to restore themechanism 12 to the thrust-transmitting condition of Fig. l. Theimportance of this reset-blockn a ti wil s on ap ar o ly- For drivingthe plunger 35 upwardly to produce the above-described closing of thecircuit breaker 12, the stored-energy closing device is relied upon.Referring to Figs. 1 and 2, this closing device 10 comprises a cylinder4Q having a piston 42 slidably mounted therein. The plunger 35 isattached to this piston 42 at its lower end by suitable means, such asby a nut 43 threaded n the plu r a sham n he pi against a shoulder 44 fr ed on h p e he p n e 3 s urged P- wardly from the position of Fig. 1by means of a heavy compression spring 45, hereinafter termed theclosing spring, which is interposed between the piston 42 and the lowerend wall 46 of the cylinder. In the position shown in Big. 1, theclosing spring 45 is fully charged and is held in this fully chargedcondition by means of a suitable latching device 48 The latching device43 may be of any suitable conventional form but preferably comprises atoggle consisting of a pair of links 49 and 50 pivotally joined togetherby a knee 51. The link 49 is pivotally connected to the plunger 35 at52, whereas the link 50 is pivotally monnted on a stationary pivot 53.The knee is restrained in the position shown in Fig. l by means of asuitable latch 54 pivoted at 55 and urged into its restraining positionby a compression spring 56. When this latch 55} is lifted by means soonto be described, the knee 51 is released, and the plunger 35 is thenfree to move upwardly. This allows the charged compression spring 45 toquickly discharge and thus drive the plunger 35 rapidly upward toproduce the desired closing of the breaker. The position of the partsafter the closing spring 45 has completed a major portion of itsdischarging action is illustrated in Fig. 2.

For lifting the latch 54 to initiate the above-described discharge ofthe closing spring 45, a solenoid 11 is provided. Referring to Fig. 1,when this solenoid 11 is energized to drive its armature upwardly, aprojection 11a carried by the armature engages the underside of thelatch 54 and carries the latch upwardly into the tripped position,thereby initiating the above-described closing action. This energizationof the solenoid is produced by closing a suitable control switch 13,which is connected series with the coil of a control relay 14 and anornally-closed set of contacts 16 across a source 15. of control power.Closing of the control switch 13 energizes the control relay 14 whichresponds by immediately closing its contacts 14a to complete anenergizing cireuit for the solenoid '11. V

- The contacts 16, which are connected in series with the coil ofcontrol relay 14, are controlled by the position of latch 54. Trippingof the latch 54 opens these contacts 16, and they remain open until thelatch 54 is reset. The purpose of these contacts 16 is to preventrelease of, the closing spring 45 prior to its being fully charged, aswill soon appear more clearly.

I The control relay 14 has a time-delay drop-out characteristic. Thus,when the control switch 13 is released after having been closed toinitiate a closing operation, the contacts 14a remain closed untilexpiration of a predetermined interval. This interval is set to havesufficient length to insure completion of the circuit breaker closingoperation. When the contacts 14a open after completion of this interval,they interrupt the energizing circuit for the solenoid 11, therebyallowing the solenoid to drop-out.

For recharging the spring 45 so as to permit additional closingoperations, pressurized liquid is supplied to the cylinder space abovethe piston 42. To provide for this pressurized liquid, the upper end ofthe cylinder 40 is fitted with a cup-shaped closure 57 acting to sealoff this upper end of the cylinder. The plunger 35 extends through acentral opening provided in the cup-shaped closure 57, and a suitableseal 58 closely surrounding the plunger prevents any fluid leakage aboutthe plunger. The closure 57 is tightly received within the cylinder 40and is retained in its position shown by means of a suitable cup-shapedretainer 59 fixed to the cylinder 40.

The cup-shaped closure 57 also serves as the body of a dump valve thatis relied upon to control the flow of pressurized liquid into and out ofthe cylinder 40. This dump valve comprises a movable valve element 60which is slidably mounted within thecylindrical body of closure 57. Theplunger 35 passes through a central opening in the valve element 60, butthis opening is of sufficient size to allow free movementof the valveelement relative to the plunger. A compression spring 62 interposedbetween the closure 57 and the movable valve element 60 urges the valveelement into its position of Fig. 1, where it is shown seated uponasuitable stop 64. In this seated position of l, the outer periphery ofthe valve element 60 acts to seal off a relatively large dump passage 66leading from the interior of cylinder 40 to a suitable sump 68. An inletpassage 69 of lesser size for supplying pressurized liquid to thecylinder 40 (in a manner soon to be described) is located above theseated position of the movable valve element 60 and can therefore supplyfluid to the interior of the cylinder 40 without restraint from thevalve element 60 so long as the valve element remains in itsseatedposition of Fig. l.

The movable valve element 60 has a plurality of orifices 7Q formed iherein for admitting liquid from. the upper side of the valve element tothe cylinder space at its lower side. A flap valve '71 carried adjacentthe lower side of valve element 60 offers no appreciable impediment tosuch downward flow but acts as a check valve for preventing reverse orupward flow of liquid through the orifices 70. This flap valve 71 isshown loosely mounted within a recess "72 formed in the lower face ofthe dump valve element 69, and retained within this recess by a suitableretaining ring 73 secured to the dump valve elernent 6t). Downward flowof liquid through the orifices 7i) forces the flap valve 71 against theretaining ring '79 and allows fluid to flow freely through the enlargedcentral opening 74 of the flap valve. However, when fluid tends to flowin an opposite or upward direction, the flap valve 71 is forced upwardlyagainst the underside of the dump valve element 66, where it acts toseal the orifices 79 and block upward flow therethrough.

For supplying pressurized liquid to the cylinder 40 through the inletpassage 69 in order to recharge the closing spring 45, a suitablereversible gear pump 75 is provided. This pump 75 is arranged to bedriven by a reversible electric motor 76 which is controlled in a mannersoon to he described. When the motor 76 drives the pump 75 in a forwarddirection, as illustrated in Fig. l. the pump forces liquid into thespace above the valve element 60 and through the orifices 76 into thecylinder space above the piston 42. The pressure within this cylinderspace quickly huilds up and acts to drive the piston 42 downwardlythereby compressing and recharging the spring 45. Near the end of thisdownward stroke, the latch 54 moves into place behind the knee 51,thereby rendering the latching device 48 again operative to hold thespring 45 in its charged conditionl When this occurs, operation of thepump 75 is terminated by opening of the motor-energizing circuit, andthe latching device 43 acts thereafter to hold the closing spring 45charged. When operation of the pump is terminated, the pressure whichhad been built up within the cylinder space begins to decay, but thelatching device 48 holds the closing spring charged despite this decayin pressure. The position of the various parts shortly after operationof the pump has been terminated is illustrated in Fig. 1.

The reversible motor 76, which controls the pump 75, can be of anysuitable conventional form but preferably comprises a pair of fieldwindings F and R, each of which is shown connected in series with thearmature of the motor. Energization of the winding F produces forwardoperation of the motor, whereas energization of the winding R producesreverse operation.

For properly controlling the motor 76 and the pump 75, I connect inseries with the reverse winding R of the motor a set of normally-opencontacts 78 which are controlled by the closure-initiating solenoid 11.When these contacts 78 are closed, they complete an energizing circuitfor the reverse winding R, thereby causing the motor to operate in areverse direction (for purposes which will soon be apparent).

For controlling the forward Winding F, a set of normally-closed contacts80 are connected in series therewith. These contacts 80 are controlledby the closureinitiating solenoid 11 and are opened by the solenoid whenit operates to initiate closure of the circuit breaker. Also connectedin series with the forward winding F is another set of contacts 82 whichare controlled in accordance with the position of latch 54. When thelatch 54 is in its reset position of Fig. 1, these contacts 82 are open,but when the latch 54 is tripped, these contacts 82 are driven closed bymeans of a suitable spring 83. Contacts 82 remain closed until the latch54 resets.

Assume now that the circuit breaker 12 is open and that it is desired toclose the breaker. If the parts of the closing device are in theposition shown in Fig. 1, this closing action can be initiated byclosing the control switch 13. As previously described in detail, thiscauses the solenoid 11 to operate, thereby tripping the latch 54 andfreeing the closing spring 45 for discharge. The closing spring respondsby driving the piston 42 and the plunger 35 rapidly upward to producethe desired circuit breaker closing action.

This upward closing movement of the piston 42 takes place withoutappreciable restraint from the liquid above the piston because of theaction of the movable dump valve element 60 during this closing period.In this regard, when the spring 45 begins to discharge and force thepiston 42 upwardly, it pressurizes the body of liquid between the piston42 and the movable valve element 60.

As illustrated in Fig. 2, this pressure acting against the underside ofthe movable valve element 60 forces the thereby uncovering therelatively large dump passage 66.

Thereafter, liquid can flow freely through this dump passage and,accordingly, very little fluid resistance is en countered by the pistonas it continues through its upward closing stroke.

When the above-described upward closing movement of the piston 42 wasinitiated, the pressurized liquidbeneath the dump valve element 60forced the flap valve 71 immediately to seat against the underside ofthe valve element. 70, thus preventing any pressure build-up above thevalve element 60 which would undesirably retard upward dumping movementof the valve element 60.

In the illustrated embodiment of my invention, upward dumping action ofthe valve element 60 is effected at high speed by relying upon reversepumping action by the pump 75. More specifically, when the solenoid 11operates to trip the closure-initiating latch 54, it also closes 'thecontacts 78 in the energizing circuit for motor windingR. This causesthe motor to drive the pump in the reverse direction illustrated in Fig.2. Such reverse pumping action quickly withdraws liquid from the spaceabove the dump valve element 60, thus allowing this valve element 60 tomove rapidly upward under the influence of fluid pressure acting againstits underside.

In those applications where it is acceptable to initiate such cases,sufficient leakage takes place through the idle gear pump to permit thevalve element 60 to move up- This blocked upward flow through theorifices wardly under the influence of pressure actingagainstiunderside. I

When the upward closing stroke of piston 42 has been completed, pressurebeneath the dump valve element 60 is insufficient to hold the valveelement in its upper position against the action of spring 62. As aresult, the spring 62 restores the valve element 60 to its lowerposition, which is depicted in Fig. 1.

Recharging of the closing spring 45 after completion of theabove-described closing action takes place as follows. Assume first thatthe operator had released the control switch 13 immediately afterinitiating this closing action. After a time interval sufliciently longto insure completion of the closing operation, the relay 14 drops out toopen its contacts 14a, thereby interrupting the energizing circuit forthe solenoid 11. This causes the solenoid 11 to drop out, therebyclosing its contacts 80 and opening its contacts 78. Opening of thecontacts 78 interrupts the energizing circuit for the reverse winding Rof the motor 75, whereas closing of the contacts 80 completes anenergizing circuit for the forward winding F of the motor. Thisterminates the reverse pumping action and initiates forward pumpingaction. Such forward pumping action forces liquid through the inletpassage 69 and the orifices 70, as indicated by the arrows in Fig. 1,thus building up fluid pressure above the piston 42. This pressurebuild-up drives the piston 42 downwardly to recharge the closing spring45. When this downward charging movement of piston 42 has progressed tothe stage where latch 54 can reset to its position of Fig. 1, thelatch-controlled contacts 82 are opened by the latch, therebyinterrupting the motor energizing circuit. This terminates thespring-charging action, and the closing device is once again prepared toproduce circuit breaker closing.

For preventing circuit-breaker pumping, i. e., inadvertent repetitiveclosing operations in the event that the breaker should fail to remainclosed while the control switch 13 is held closed, the control relay 14is provided with a set of seal-in contacts 14b'which are operated toclosed position when the control relay 14 is picked-up to initiatecircuit-breaker closing. Closing of these contacts 14b completes aseal-in circuit through the switch 13, the coil of relay 14, and thecontacts 14b, which holds the relay 14 in an operated position so longas the control switch 13 is held closed. This holds the contacts 14aclosed so long as the control switch 13 is held closed, thus maintainingthe solenoid 11 energized and its contacts 80 open so long as thecontrol switch 13 is held closed. Since the contacts 80 are relied uponfor initiating a recharging operation, so long as they are held open,recharging is prevented. Thus, holding the control switch 13 closed willprevent recharging after a closing op- 1 become accidentallyde-energized before the charging operation is completed, say, as aresult of loss of control power, then the resulting discharge of thespring 45 should not act to drive the contact 18 toward closed position.This objective is attained in my closing arrangement by preventing thetrip-free linkage M from resetting to a thrust-transmitting conditionuntil the springcharging operation has been completed. For example,referring to Fig. 3, the mechanism resetting spring 38 is incapable ofresetting the mechanism until the plunger 35 has been lowered to aposition in which the closing spring 45 is fully charged. Thus, if theclosing spring 45 should be prematurely allowed to discharge, it wouldsimply drive the plunger 35 upwardly without transmitting closing thrustto the movable contact '18.

The contacts 16 also aid in preventing release of the closing spring 45prior to its being fully charged. These contacts, 16 remain open so longas the latch 54 is in its tripped position and close only when the latchresets in response to completion of a recharging operation. So long asthese contacts 16 remain open, the solenoid 11 is prevented from beingagain energized as a result of closing the control switch 13. Thus, thesolenoid is disabled from initiating a closing action prior to fullrecharging of the closing spring 45.

Once the closing spring 45 begins discharging to initiate the usualcircuit-breaker closing operation, it is important that this operationalways be carried through to completion without interference oropposition from operation of the pump 75. For example, if, for anyreason, the pump 75 should become prematurely operated in aspring-charging, or forward, direction during the spring-discharginginterval, then such operation should not be allowed to oppose thedischarging of the spring. This objective is attained in my arrangementby relying upon the movable dump valve element 6t) to block flow throughthe inlet 69 during a spring-discharging operaation. For example, duringsubstantially the entire springdischarging action, the valve element 60is in its elevated position of Fig, 2 where it seals off the inlet 69and therefore prevents the fiow of liquid from the pump into thecylinder space.

In those applications in which it is desired to efiect automaticreclosing of the above-.describedcircuit breaker, the closing controlswitch 13 is arranged to close automatically in :response to abreaker-opening operation, thereby initiating an automatic reclosure.Circuits for providing this desired control over the closing controlswitch 13 are well known, and reference may be had to Stewart Patent1,943,096, assigned to the assignee of this application, for an exampleofsuch a circuit.

It may be desirable in certain of these reclosing applications to delaythe automatic reclosing operation until a predetermined interval of timehas elapsed after circuit breaker opening. Such a delay can be readilyobtained .in my disclosed operating device by providing in the inletline 69 a valve such as shown at 90 in Fig. 4. Thi valve 90 comprises amovable element 91 which is biased by means of a light spring .92 intoengagement witha suitable seat 93 on the pump or upstream side of thevalve. Flow from thepump forces the valve element 91 off of its seat,and fluid from the pump is thereafter able to flow relatively freelyabout the outer periphery of the element 21 toward the main operatingcylinder 4%). Thus, the valve 'oflers .no appreciable impedance to thatflow which is relied upon to charge the main spring 45. However, whenflow takes place in a reverse direction through the valve 90, asindicated by the arrows of Fig. 4, element 9 1.is forced against theseat 93, and any fluid flowing in this reverse direction is required toflow through a restricted orifice 94.

The rate at which this flow in a reverse direction takes placegovernsthespeed'at which the previously described dumping movementof the mainvalve elements 60 takes place and, correspondingly, the rate at whichdischarge of the closing spring 45 is initiated. The size of the orifice9 4 governs this rate of reverse flow. Hence, by a suitable choice ofthe size of restricted orifice 94; a desired delay in reclosing can beobtained.

While I have shown and described particular embodiments of my invention,it will be obvious to those skilled .in the art that various changes andmodifications can be .made without departingfrorn my invention in itsbroader aspects, and I therefore intend in the appended claims to coverall such changes and modifications as fall within the true spirit andscope of my invention.

What I claim as new and desire to secure by Letters 'Patent .oftheUnited States is:

.1 In an electric circuit breaker, a chargeable closing spring ich i slis ar hls t slosersaid br sken cylinder, a movable piston mounted withinsaid cylinder a ope atively c u ed to n a d 9? sa d S n me for supplyingpressurized fluid to the cylinder space at one side of said piston fordriving said piston in a first direction to charge said spring,releasable restraining means for holding said piston in a position tomaintain said spring charged, means for subsequently releasing saidrestraining means to allow said spring to discharge at said one end anddrive said piston in a direction opposite to said first direction, meansactuated by piston movement in said opposite direction for closing saidcircuit breaker, a dump passage leading from said cylinder space, amovable valve member blocking flow through said dump passage duringcharging of said spring, and means operable after completionpf saidspring-charging operation for moving said valve member out of blockingrelationship relative to said dump passage whereby to allow said springduring discharge to drive said piston in said opposite direction withoutappreciable restraint from fluid in said cylinder space. l i

2. In an electric circuit breaker, a chargeable closing spring which isdischargeable at one of its ends to close said breaker, a cylinder, amovable piston mounted within said cylinder and operatively coupled tosaid one end of said spring, means for supplying pressurized fluid tothe cylinder space at one side of said piston for driving said piston ina first direction to apply spring-charging force to said one end of saidspring, releasable restraining means for holding said piston in aposition to maintain said spring charged, means for subsequentlyreleasing said restraining means to allow said spring to discharge atsaid one end and drive said piston in a direction opposite to said firstdirection, means actuated by piston movement in said opposite directionfor closing said circuit breaker, a dump passage leading from saidcylinder space, a movable valve member blocking flow through said dumppassage during charging of said spring, and means operable upon releaseof said restraining means for moving said valve member out of blockingrelationship with said dump passage, said valve member being maintainedin said non-blocking position during spring-discharge by fluid pressureforces pro duced by said spring-discharge, and means for returning saidvalve member to said blocking position upon completion of saidspring-discharging action.

3. In an electric circuit breaker, a chargeable closing spring which isdischargeable to close said breaker, a cylinder, a movable pistonmounted Within said cylinder and operatively coupled to one end of saidspring, means for supplying pressurized fluid to the cylinder space atone side of said piston for driving said piston in a first direc tion tocharge said spring,'releasable restraining means for holding said pistonin a position to maintain'said spring charged, means for subsequentlyreleasing saidrestraining means to allow said spring to discharge atsaid one end and drive said piston in a direction opposite to said firstdirection, means actuated by piston movement in said opposite directionfor closing said circuit breaker and means for quickly discharging fluidfrom said cylinder space when the piston moves in said oppositedirection whereby to allow circuit-breaker closing to take place withoutappreciable restraint from fluid in said cylinder space.

4. In an electric circuit breaker, a chargeable spring which isdischargeable at one of its ends to close said breaker, a cylinder, amovable piston mounted within said cylinder and operatively coupled tosaid one end of said spring, means for supplying pressurized fluid tothe cylinder space at one side of said piston for driving said piston ina first direction to charge said spring, releasable restraining meansfor holding said piston in a position to maintain said spring charged,means for subsequently releasing said restraining means to allow saidspring to discharge atsaid oneend and drive said piston in a direc; tionopposite to said first direction, a dump passage leading fromsaidcylinder space, a movable valve member blocking flow through saiddump passage during charging of said spring, and means operable uponrelease of said restraining means for moving said valve member into aposition for blocking flow into said cylinder space and for allowingflow out of said cylinder space through said dump passage.

5. In an electric circuit breaker, a chargeable closing spring which isdischargeable to close said breaker, a cylinder, a movable pistonmounted within said cylinder and operatively coupled to said spring, afirst passageway leading into the cylinder space at one side of saidpiston, means for supplying pressurized fluid to said cylinder spacethrough said first passageway to drive said piston in a direction tocharge said spring, releasable restraining means for holding said pistonin a position to maintain said spring charged, means for subsequentlyreleasing said restraining means to allow said spring to discharge anddrive said piston in a direction opposite to said charging direction,means actuated by piston movement in said opposite direction for closingsaid breaker, a dump passage leading from said cylinder space, a movablevalve member blocking flow through said dump passage during the timefluid is flowing through said first passageway to charge said spring,and means operable upon release of said restraining means for movingsaid valve member out of blocking relationship with said dump passageand into blocking relationship with said first passage.

6. In an electric circuit breaker, a chargeable closing spring which isdischargeable to close said breaker, a cylinder, a movable pistonmounted within said cylinder and operatively coupled to said spring, afirst passageway leading into the cylinder space at one side of saidpiston, pumping means for supplying pressurized fluid to said cylinderspace through said first passageway for driving said piston in adirection to charge said spring, releasable restraining means forholding said piston in a position to maintain said spring charged,closure-initiating means for subsequently releasing said restrainingmeans to allow said spring to discharge and drive said piston in adirection opposite to said charging direction, means actuated by pistonmovement in said opposite direction for closing said breaker, a dumppassage leading from said cylinder space, a movable valve memberblocking flow through said dump passage during the time fluid is flowingthrough said first passageway to charge said spring, means operable uponrelease of said restraining means for eifecting dumping movement of saidvalve member out of blocking relationship with said dump passage, andmeans controlled by said closure-initiating means for causing saidpumping means to withdraw from the region of said valve member fluidtending to retard dumping movement of said valve member whereby toaccelerate said dumping movement.

7. The combination of claim 6 in which said dumping movement of thevalve member positions the valve member in blocking relationship withsaid first passageway.

8. In an electric circuit breaker, a chargeable spring which isdischargeable to close said breaker, a cylinder, a piston movablymounted within said cylinder and operatively coupled to said spring,reversible pumping means operable in a forward sense to supplypressurized fluid to the cylinder space at one side of said piston fordriving said piston in a first direction to charge said spring,releasable restraining means for holding said piston in a position tomaintain said spring charged, means for subsequently releasing saidrestraining means to allow said spring to discharge and drive saidpiston in a direction opposite to said first direction, a dump passageleading from said cylinder space, a movable valve member blocking flowthrough said dump passage during charging of said spring, means operableupon release of said restraining means for eflecting dumping movement ofsaid valve member out of blocking relationship with said dump passage,and means for accelerating said dumping movement of said valve member bycausing said pumping means to operate in a reverse sense and removeliquid from ahead of the valve member during said dumping movement.

9. In an electric circuit breaker, a chargeable closing spring which isdischargeable to close said breaker, a cylinder, a movable pistonmounted within said cylinder and operatively coupled to said spring, afirst passageway leading into the cylinder space at one side of saidpiston, means for supplying pressurized fluid in a forward directionthrough said first passageway to drive said piston in a direction tocharge said spring, closure-initiating means for subsequently causingsaid spring to discharge and drive said piston in a direction oppositeto said charging direction, means actuated by piston movement in saidopposite direction for closing said breaker, a dump passage leading fromsaid cylinder space, a movable valve member blocking flow through saiddump passage during the time fluid is flowing through said firstpassageway to charge said spring, means responsive to operation of saidclosure-initiating means for effecting dumping movement of said valvemember out of blocking relationship with said dump passage, said firstpassageway acting as an outlet through which fluid flows reversely fromahead of said valve member during said dumping movement, auxiliary valvemeans disposed in said passageway for providing a comparatively highimpedance to the reverse flow of fluid through said passageway wherebyto retard said dumping movement, and means for causing said auxiliaryvalve to provide a substantially lesser impedance to fluid flowingthrough said passageway in a forward direction.

10. In an electric circuit breaker having separable contacts, atrip-free linkage coupled to one of said contacts, said linkage beinginoperable to transmit closing power to said contact when in a trippedcondition and being operable to transmit'closing power to said contactwhen in a reset condition, a chargeable closing spring which isdischargeable to provide said closing power, a cylinder, a movablepiston mounted within said cylinder and operatively coupled to one endof said spring, means for supplying pressurized fluid to the cylinderspace at one side of said piston for driving said piston in a firstdirection to charge said spring, means for subsequently allowing saidspring to discharge at said one end and supply closing power to saidlinkage, resetting means tending to reset said linkage after trippingthereof, and means connected to said piston for blocking resetting ofsaid linkage until said piston has been moved through a predeterminedcharging stroke, said resetting means acting to reset said linkage whensaid predetermined charging stroke has been completed.

11. In an electric circuit breaker, a chargeable spring which isdischargeable to close said breaker, a cylinder, a piston movablymounted within said cylinder and operatively coupled to said spring,reversible pumping means operable in a forward sense to supplypressurized fluid to the cylinder space at one side of said piston fordriving said piston in a first direction to charge said spring,releasable restraining means for holding said piston in a position tomaintain said spring charged, means for subequently releasing saidrestraining means to allow said spring to discharge and drive saidpiston in a direction opposite to said first direction, means actuatedby piston movement in said opposite direction for closing said circuitbreaker, means for operating said pump in a reverse sense to removefluid from said cylinder space, and means controlled by said reverseoperation of the pumping means for controlling the rate at which pistonmovement in said opposite direction is initiated.

References Cited in the file of this patent UNITED STATES PATENTS1,724,776 Rankin Aug. 13, 1929 2,381,203 Bush Aug. 7, 1945 2,578,349Goodwin Dec. 11, 1951

